Pharmacology/Alpha 2 agonists

Alpha 2 receptors are located mainly on presynaptic nerve endings, as well as Beta cells of the pancreas. These receptors are inhibitory in nature. When Norepinephrine is released from the presynaptic nerve terminal, some circles back to bind with the Alpha 2 receptor. This causes feedback inhibition, thus reducing the amount of Norepinephrine released. Alpha 2 stimulation also results in inhibition of insulin release. Binding of Alpha 2 receptors is mediated by inhibition of adenylyl cyclase and a decrease in the amount of intracellular cAMP. Alpha 2 agonists include Norepinephrine and Clonidine.